Method of producing aromatic hydrocarbons



mentes July 31,1945

UNITED STATES A'lul'l'lanrr- LoFi-ICE monol- Norman E Lhm.

,Westel rnonoomo aaona'nc n ocnnons milch-lo..

lv, l..

'Imbert NJ.. Ildmorltostanb' ardilompany,acorporationol Aem Anim se. 1942. selln ne. 456,614

4 Claims. (Cl. 2Gb-6684) countercurrently to the -rising vapors. TheV efiective solvent/oil ratio in the tower is from about ltoLioBtolbyvolume.

llll'om the top of the column 3 normally gaseous hydrocarbons such as methane, ethane, prol pane, and pentane and the'corresponding oleilns are withdrawn through line Il, and these substances may be processed in any desired manner to convert then to valuable products. Thus. they' may be subjected to alkyltion where say y an isoparailin is reacted with an olefin, or the we are aware generally relate to the conversion of Y a substantially pure compolmd, such as normal Y heptane. to toluene by cycllzation andaromat-ization in the presence oi' a suitable catalyst. Obviously the amount of toluene produced by such a process from a given quantity oi' oil containing normal heptane is limited by the narrowness oi the boiling range of the charging stock.

According to our process. we are enabled to ob-y tain a greater yiell of aromatlcs from a given original feed stock than has beenobtainable heretofore, as' will more fully appear hereinafter.v

- The main object of our invention is directed toward producing a maximum quantity-oi' aromatics from a hydrocarbon oil, such as a naphtha traction.

other and further objects er eur lnvenaenwlll appear from the following more detailed description and claims.

-Tms inventions especially epolleeble to the.

production of maximum quantities oi' aromati from relatively narrow boiling range hydrocarbon fractions. In-the description which follows the hydrocarbon feed comprises a fraction boiling between about 190 and 240 F. by the Engler'V distillation procedure and contains such hydrocarbons as toluene, methyl cyclohexane, 'dimethyl cyclopentane, heptanes and the like.

ln the accompanying drawins, we have 'shown uenllysuewplanlllustratinsare-J Y fen'ed modincation oi' our invention.

Referring in detail to the drawing. feedstock comprisinganaphtha (virginorcracked) boiling within the range oi' fromv 190 to 240 1"., is discharsedintothesystemthroushlinelandafter suitable heating is discharged into a solvent ex-l traction none I where it is subjected to solvent extraction. The oil-entering the extracon colnormal butanes may be dehydrogenatedto formV intermediates such 'as butadiene useful in synthetic rubber-synthesis, or the products may be otherwise disposed of ln'known manner. A side fraction which is largely paramnic but may contain some oleiins is withdrawn as a raiilnate through line I2. A portion oi' -this stream may be returnedas reiiuxthroushline Theproducts stream is then heated in a furnace or the like Il to a temperature of from 280 to 350 F., then discharged through line I5 into a. ilash tower Jl from which the overhead product comprising v substantially paraillns is withdrawn through line 20. In thecase where a solvent such as phenol 'or another high boiling solvent is present in extraction tower l, the solvent carried over with the ramnate phase in line Il may be separated in flash tower Il and withdrawn through line 22.v The paramns in lille 2l are discharged into a cyclisation and aromatlzaon zone 25 where they are subjected to temperatures of within the range er from 'lso te 1200*' F. and pressures ef 5o te 40o lbs. per square inch. Cyclization and aromatization vessel contains a catalyst preferably disposed on a ioraminous tray T. The catalyst may consist of C110: supported on Activated Alumina,

ox--it may consist of metallic nickel, or it may consist oi' chromium oxideor gelor simply oxides of chromium, vanadium, titanium, thorium, andv ceriumdeposited or alumina or magnesia. These catalystsareknown tothealt.y Torepress coke formation we prefer tochargc to reactor 2B via line lI-a and line 2l a quantity of hydrogen or hydrogen-containing sas.

As tp feed rates,- the cyclization are lcd to unit 2l at errate of .from (L1-5 liquid volumes per volume of catalyst per umnisinvaporiormanldhasatemperaialreotV 200 to 235 l". The solvent which maybe liquid phenol or the likefat a temperature o! about wlisdischargedintothetopotthe columnthrough line l and glows downwardiy'and heur, with a reed rete e: n.1 te 1.o preferred. The

' reaction'products are withdrawn from unit' i5 .through line YIl Yand thence discharged into vu. distillation tower Si, vthe operation of which will be more Vfully explained, hereinafter.

Referring back to solvent extraction column l 1|.vv fraction predominantly 'naphthenic -or cycloparamos undergoing rxomsomesuitablesomcethroughline" l throughthereactorduringthedehydrogenation,

stock trom reactor 2i and/orreactor Il, thence withdrawn mmgh une umd discharged inw a distillation acne l! from which thearomatics may be withdrawn through line Si. The .solvent ia withdrawn from the bottom. of zone Ill throlmh to the top line lll and returned through line o! extraction tower 3. A

Nitratiom grade toluene can be prepared from tion zone l! through line 8i by' simply acid treating and redistillig the fraction boiling between 228 F.- and 231 F. Thus the product in line" containing aromatics will also contain some olenns. and we therefore treat the product with suliheemmatic'product discharged from distiller phurlc acid in vessel ll'i'n order to polymerize 'the olenns, nally discharging them into a iinishing still all where the polymerized olens may be separated fromthe aromatica by distillation as anoverhead product. 5 l

Referring back to the products 'in lines l0 and. 6l, respectively, 'the same maybe. as indicated,

or others may be undergoing regeneration or its catalyst.' f

Itisalsowithin the-scope ofourinvention-to employinsteadofthepilledcatalystinreactors 2l andilwherethecatalyrtisdntheform oa stationarybedorbeds.toemploy catalystinpowdertormsuspendedoriiuidizedbythevapors undergoing reaction. supplemented if necsary byothermeans; Theprecisedetailsotoperatins thereactorsandthesolventertractionsonedo notpersetormtheessenceofourinveution.

wnue the. above invention has described 'they erably in vaporform, in treated with a liquid solvent auch as phenol, and in an extraction zone the charged stock is divided into relatively narrow boiling range aromatica, naphthenes. and yand after separation of the aromatica from the naphthenes and paramos we propose to dehydrogen'ate the former and cyclize and aro .matize the latter, combining these formed ammaties with the aromatics originally present in the feed stock and-thus secure. a high yield o! aromatica.

discharged into distillation tower l5 by operation 75 Many mod'iiications falling thel scope of our invention will suggest themselves to those who are familiar with this art.

What we claim is:

1. An improved process for the production of nitrationgrade toluene from a hydrocarbon fraction containing paraillns, naphthenesl andaromatics and boiling in the range between about 190 and 240 F. which comprises solvent extracting said hydrocarbon fraction with a liquid preferential solvent for aromatics at a temperature between about 200 and 220-F. in a solvent treating zone, withdrawing from said zone a hydrocarbon stream rich in paraffins, a hydrocarbon stream rich in napththenes, and a hydrocarbon stream rich in,aromatics, separately subjecting said paramnic stream to aromatization in the presence of a catalyst selected from the group consisting oi' the oxides of chromium, molybdenum and vanadium, and in the presence of a recirculating stream of hydrogen maintained at a pressure between 50 and 300 lbs. per square inch, separately subjecting said naphthenic stream to hydroforming in the presence of a catalyst consisting of from 3 to 20% of molybdenum oxide supported on Activated Alumina, and in the presence of a recirculating stream o f hydrogen ly subjecting said fraction enriched in paralns to catalytic aromatization, separately subjecting said fraction enriched in naphthenes to catalytic dehydrogenation in the presence of a stream of hydrogen, combining the products of aromatization and dehydrogenation boiling in the range between about 240 and 300 F. and subjecting the combined products to solvent extraction in maintained at a pressure between 50 and 300 i lbs. per square inch, said hydrogen stream containing between and 80 mol percent hydrogen, combining the products oi' aromatization and hydroforming, subjecting said combined products to vapor-liquid solvent extraction, removing from said solvent extraction an aromatic fraction, passing said aromatic fraction to a distillation zone, recovering from said zone a fraction boiling between about 228 and 231 F., washing thc fraction boiling between about 228 and 231 F. with sulfuric acid to remove olens, and redistilling to obtain thereby substantially pure toluene.

2. An improved process for the production 0f substantially pure xylenes from a hydrocarbon fraction containing paranlns, naphthenes and aromatica and boiling in the range between about 240 and 300 F. which comprises vaporizing said hydrocarbon fraction, subjecting the vaporized hydrocarbons to' solvent extraction with a solvent in the liquid state, segregating thereby three fractions enriched respectively in paramnic, naphthenic and aromatic constituents, separate- A4000 cubic feet per barrel and in which a pressure between about and 400 lbs. per square inch pressure is improved on the system.

4. An improved process for the production of substantially pure xylenes from a hydrocarbon fraction containing paraflins, naphthenes and aromatics and boiling in the range between about 240 and 300 F. which comprises vaporizing said hydrocarbon fraction, subjecting the vaporized hydrocarbons to solvent extraction with a solvent in the liquid state, segregating thereby three fractions enriched respectively in paraillnic, naphthenic and aromatic constituents, separately sub.. jecting said fraction enriched in paraillns to catalytic aromatization, separating subjecting said fraction enriched in naphthenes to catalytic dehydrogenation in the presence o1' a stream of hydrogen, combining the products'of aromatization and dehydrogenation boiling in the range between about 240 and 300 F. and subjecting the combined products to solvent, extraction in the said solvent extraction zone, removing from said solvent extraction vzone an extract phase enriched in xylenes, and stripping said extract phase of extract to obtain a streamv of hydrocarbons containing substantially only xylenes.

NORMAN F. LINN. CARL O. TONGBERG.

Certilcate of Correction Patent No. 2,380,853.

July 31, 1945.

NORMAN F. LINN ET AL.

I t is hereby certified that errors 'appear in the printed specification of the above numbered patent reouiring correction' as follows: Page 3, first column, line 14, claim l, for napththenesv read naphthenes; and second co umn, line 35, claim 4, for separating read separately; line 41Lgame claim, after the Words to solvent" strike out the comma; and that the said therein that the same may conform tters Patent should be read with these corrections to the record of the case in the Patent Oice.

Sigied and sealed of Marcha. 11,1947;

[ma] i our invention will suggest themselves to those who are familiar with this art.

What we claim is:

1. An improved process for the production of nitrationgrade toluene from a hydrocarbon fraction containing paraillns, naphthenesl andaromatics and boiling in the range between about 190 and 240 F. which comprises solvent extracting said hydrocarbon fraction with a liquid preferential solvent for aromatics at a temperature between about 200 and 220-F. in a solvent treating zone, withdrawing from said zone a hydrocarbon stream rich in paraffins, a hydrocarbon stream rich in napththenes, and a hydrocarbon stream rich in,aromatics, separately subjecting said paramnic stream to aromatization in the presence of a catalyst selected from the group consisting oi' the oxides of chromium, molybdenum and vanadium, and in the presence of a recirculating stream of hydrogen maintained at a pressure between 50 and 300 lbs. per square inch, separately subjecting said naphthenic stream to hydroforming in the presence of a catalyst consisting of from 3 to 20% of molybdenum oxide supported on Activated Alumina, and in the presence of a recirculating stream o f hydrogen ly subjecting said fraction enriched in paralns to catalytic aromatization, separately subjecting said fraction enriched in naphthenes to catalytic dehydrogenation in the presence of a stream of hydrogen, combining the products of aromatization and dehydrogenation boiling in the range between about 240 and 300 F. and subjecting the combined products to solvent extraction in maintained at a pressure between 50 and 300 i lbs. per square inch, said hydrogen stream containing between and 80 mol percent hydrogen, combining the products oi' aromatization and hydroforming, subjecting said combined products to vapor-liquid solvent extraction, removing from said solvent extraction an aromatic fraction, passing said aromatic fraction to a distillation zone, recovering from said zone a fraction boiling between about 228 and 231 F., washing thc fraction boiling between about 228 and 231 F. with sulfuric acid to remove olens, and redistilling to obtain thereby substantially pure toluene.

2. An improved process for the production 0f substantially pure xylenes from a hydrocarbon fraction containing paranlns, naphthenes and aromatica and boiling in the range between about 240 and 300 F. which comprises vaporizing said hydrocarbon fraction, subjecting the vaporized hydrocarbons to' solvent extraction with a solvent in the liquid state, segregating thereby three fractions enriched respectively in paramnic, naphthenic and aromatic constituents, separate- A4000 cubic feet per barrel and in which a pressure between about and 400 lbs. per square inch pressure is improved on the system.

4. An improved process for the production of substantially pure xylenes from a hydrocarbon fraction containing paraflins, naphthenes and aromatics and boiling in the range between about 240 and 300 F. which comprises vaporizing said hydrocarbon fraction, subjecting the vaporized hydrocarbons to solvent extraction with a solvent in the liquid state, segregating thereby three fractions enriched respectively in paraillnic, naphthenic and aromatic constituents, separately sub.. jecting said fraction enriched in paraillns to catalytic aromatization, separating subjecting said fraction enriched in naphthenes to catalytic dehydrogenation in the presence o1' a stream of hydrogen, combining the products'of aromatization and dehydrogenation boiling in the range between about 240 and 300 F. and subjecting the combined products to solvent, extraction in the said solvent extraction zone, removing from said solvent extraction vzone an extract phase enriched in xylenes, and stripping said extract phase of extract to obtain a streamv of hydrocarbons containing substantially only xylenes.

NORMAN F. LINN. CARL O. TONGBERG.

Certilcate of Correction Patent No. 2,380,853.

July 31, 1945.

NORMAN F. LINN ET AL.

I t is hereby certified that errors 'appear in the printed specification of the above numbered patent reouiring correction' as follows: Page 3, first column, line 14, claim l, for napththenesv read naphthenes; and second co umn, line 35, claim 4, for separating read separately; line 41Lgame claim, after the Words to solvent" strike out the comma; and that the said therein that the same may conform tters Patent should be read with these corrections to the record of the case in the Patent Oice.

Sigied and sealed of Marcha. 11,1947;

[ma] i 

